Clinical meaning
Brown-Séquard syndrome results from lateral hemisection of the spinal cord, producing a characteristic pattern of ipsilateral motor paralysis and proprioception loss below the lesion, with contralateral loss of pain and temperature sensation beginning one to two segments below the level of injury. This pattern occurs because the corticospinal tract (motor) and dorsal columns (proprioception, vibration, fine touch) cross at the medulla, so they are affected on the same side as the lesion. The spinothalamic tract (pain, temperature, crude touch) crosses at the spinal cord level of entry, so it is affected on the opposite side. Common causes include penetrating trauma, spinal tumors, and multiple sclerosis.
Exam relevance
Risk factors: - Penetrating spinal trauma (stab wounds, gunshot injuries) - Spinal cord tumors causing asymmetric compression - Multiple sclerosis with demyelinating plaques - Spinal cord infarction (anterior spinal artery territory) - Epidural hematoma or abscess compressing one side of the cord
Diagnostics: - MRI of the spine to visualize hemisection lesion - Detailed neurological examination mapping motor and sensory deficits - CT myelography if MRI contraindicated - Motor strength testing using Medical Research Council scale - Sensory testing for light touch, pain, temperature, vibration, and proprioception